Mining Ready PSUs

We initiate a new program, through which we find the most suitable PSUs for mining or in general highly stressful applications where besides high efficiency, high performance and increased reliability are also required.

Most of you have probably heard of Bitcoin, the coin that initiated the mining frenzy. Currently there is a great number of crypto currencies and it is still profitable to mine some of them using a plain desktop PC instead of using a special ASIC (Application-Specific Integrated Circuit). Briefly mining is a record-keeping service which demands of huge processing power, leading miners who use PCs for this process to take advantage of the raw power that GPUs provide instead of utilizing the system’s CPU(s). The problem is that GPUs have to operate under full load conditions highly stressing the power supply (PSU). We should stress here however that even ASICs (like the popular Antminer systems) use normal, desktop PSUs. So besides a highly efficient PSU, in order to keep the electricity cost as low as possible, you also need a reliable unit which will be able to operate 24/7 under highly stressful conditions without sweating. As expected the PSU’s noise doesn’t concern miners since most crypto-currency farming facilities operate in dedicated spaces where the operators don’t have to stay long; even home miners should install their mining systems in isolated spaces, where noise won’t be a problem. As a matter of fact, in PSUs used for mining purposes the fan is expected to operate close to its full speed most of the time, given the high load output, effectively cooling down sensitive components which dramatically affect a PSU’s reliability (e.g. the electrolytic capacitors of the secondary side).

Our purpose isn’t to torture test each and every PSU that a manufacturer sends for certification since we already do this in our 10-110% load tests (conducted in the ETA certification), during which we overload the PSU with the ambient temperature exceeding 45°C, but mostly to examine closely its components in order to find out whether it will survive on the long run. For example a PSU with a bulk cap which is rated at 85°C will have a significantly shorter lifetime compared to a PSU with a 105°C rated bulk cap. The same applies of course to the filtering capacitors on the secondary side. A PSU that uses low quality filtering capacitors with 1-3,000 hours lifetime under 105°C won’t last as long as a PSU that uses 6-10,000 hours caps rated at the same temperature. Another important factor is the cooling fan, since if the fan breaks down then the PSU will most likely follow immediately, especially if it doesn’t have Over Temperature Protection.

We have two mining PSU categorys: Home Mining and Professional Mining.

We define home miners as users dabbling in cryptocurrency mining on the side. Those users don't want to spend a fortune building dedicated mining machines. Instead, they're looking for something that'll yield some profit and won't cost much. The home miner's rigs are running somewhere inside the house, subjected to reasonable ambient temperatures. Still, noise can't be allowed to get out of control.

Pro miners are more extreme users with systems installed in dedicated spaces (farms), many of which lack air conditioning. We have to anticipate higher ambient temperatures as a result (as high as 40?C in some cases!). Even if a farm is equipped with HVAC, imagine how hard it is to maintain comfortable temperatures, given the massive thermal output of 10s or 100s of fully utilized GPUs. This is why, for our professional mining category, we only accept PSUs equipped with ball-bearing or magnetic bearing fans. Any FDB-derivative fan is bound to fail quickly because its lubricant evaporates under such harsh conditions. Since mining farms are typically isolated from where people eat, sleep, or work, noise isn't as much of a concern. In fact, we embrace aggressive fan profiles; they're often what keeps a PSU alive under full load in a hot room.

In order to provide a Home Mining Ready certification we expect a PSU to meet all of the requirements listed below. The ideal home mining PSU should also meet our recommendations.

Lower than 50mV ripple at +12V under full load at increased operating temperatures (>40°C).

Quality fan (FDB or similar; ideally it should use ball or magnetic bearings).

At least six 6+2 pin PCIe connectors on PSUs with up to 1.1kW capacity.For PSUs with over 1.1 kW capacity the number of minimum 6+2 pin PCIe connectors is eight and for PSUs with over 1.45 kW capacity the minimum is ten 6+2 pin PCIe connectors.

At least four 4-pin Molex connectors on two at least cables, in 1 kW and stronger PSUs, and six 4-pin Molex connectors in three or more cables for 1.45 kW and higher wattage PSUs. In case the PSU has more 6+2 pin PCIe connectors than the required, we are covered with 4-pin Molex connectors regardless capacity.

All peripheral cables should use 18AWG wires minimum.

For 1.4kW and stronger PSUs a C19 coupler is required, while an AC power cord with 14AWG wires should be used. For lower capacity PSUs an AC power cord with 16AWG gauges at least is required.

The essential protection features (SCP, OPP) including Over Temperature Protection.

Over 17ms hold-up time and an accurate power-good signal, which has to be at least 16ms. The power-good signal has to have at least a 1ms delay, dropping at least 1ms before the rails go out of spec.

Complete EMI filtering stage (minimum components: 4x Y caps, 2x X caps, two CM chokes, an MOV) along with inrush current protection (an NTC thermistor is required which ideally should be supported by a bypass relay).

Impeccable build quality including quality MOSFETs, high quality bulk and filtering capacitors (105°C and the majority of filtering caps on the secondary side much have higher than 4,000h lifetime). The use of polymer caps on the secondary side is preferred.

Recommendations

Two EPS connectors.

Ideally the peripheral connectors should have 15cm distance between them.

Dedicated cables with 6+2 pin PCIe connectors are preferred. In case a cable hosts two PCIe connectors, it needs to have 16AWG gauges up to the first connector for the six out of the eight pins at least.

Every PSU with 1.3kW or more capacity should use an AC power cord with 14AWG gauges and a C19 coupler.

One year minimum warranty for 24/7 operation under full load at 30-35°C

In order to provide a Professional Mining Ready certification we expect a PSU to meet all of the requirements listed below. The ideal professional mining PSU should also meet our recommendations.

At least four 4-pin Molex connectors on two cables, or six 4-pin Molex connectors on three or more cables for PSUs with over 1.45kW capacity. In case the PSU has more 6+2 pin PCIe connectors than the required, we are covered with 4-pin Molex connectors regardless capacity.

All peripheral cables should use 18AWG wires minimum.

For 1.4kW and stronger PSUs a C19 coupler is required, while an AC power cord with 14AWG wires should be used. For lower capacity PSUs an AC power cord with 16AWG gauges at least is required. The AC power cord requirement applies only if the PSU is provided with an AC power cord.

The essential protection features (SCP, OPP) including Over Temperature Protection.

Accurate power-good signal. The power-good signal has to have at least a 1ms delay, dropping at least 1ms before the rails go out of spec.

Complete EMI filtering stage (minimum components: 4x Y caps, 2x X caps, two CM chokes, an MOV) along with inrush current protection (an NTC thermistor is required which ideally should be supported by a bypass relay).

Impeccable build quality including quality MOSFETs, high quality bulk and filtering capacitors (105°C and the majority of filtering caps on the secondary side much have higher than 5,000h lifetime). The use of polymer caps on the secondary side is preferred.

Recommendations

Ideally the peripheral connectors should have 15cm distance between them.

Dedicated cables with 6+2 pin PCIe connectors are preferred. In case a cable hosts two PCIe connectors, it needs to have 16AWG gauges up to the first connector for the six out of the eight pins at least.

Every PSU with 1.3kW or more capacity should use an AC power cord with 14AWG gauges and a C19 coupler.

Over 17ms hold-up time and an accurate power-good signal, which has to be at least 16ms. The power-good signal has to have at least a 1ms delay, dropping at least 1ms before the rails go out of spec.

One year minimum warranty for 24/7 operation under full load at 35-40°C

Home VS Pro Mining Certification

The major differences between our home and professional cryptocurrency mining PSU requirements are the capacity, efficiency, and fan specifications. Also, notice that there is no output noise ceiling in this category, and we're also recommending at least one year of warranty coverage for 24/7 operation under full load at 35-40°C for Pro mining units and 30-35°C for home mining PSUs.

We plan to create a separate database for Mining Ready PSUs, once we have enough data at our disposal to support it. Meanwhile we will only provide this information on demand along with the corresponding badges to the brands that will send us evaluation samples.

We expect the mining community to help us improve/upgrade our requirements for a Mining Ready PSU. If you have any suggestions or a new test in mind in order to feel more confident about your next PSU purchase, feel free to share your thoughts with us at info@cybenetics.com. Finally, if you own a mining facility and you are concerned about your next PSU order, you can send us samples of the candidate PSUs. We will thoroughly test them within a short period, suggesting the best options given your demands.